A brake system of the type described above German Patent application is known from the P 38 42 699.4 filed Dec. 19, 1988. The differential pressure limiter ensures that a defined pressure prevails a cross the inlet valve. It has been proven that employment of this arrangement reduces the switching noises made by the inlet valve considerably. Yet there is also created a disadvantage: the inlet valve exhibits a throttling characteristic when in its opened position. On the one hand, this is due to design reasons, since the valve passage cannot be opened as wide as desired. On the other hand, however, there are considerations in respect of control technology: the velocity of pressure increase is to be limited in the pressure-build-up phase of a braking operation with anti-lock control in order to prevent the pressure from rising beyond a specific amount.
Once the master brake cylinder is actuated quickly and abruptly during braking without anti-lock control, a large quantity of pressure fluid is pressed through the throttle of the inlet valve in a short time. This causes a pressure difference across the inlet valve, the consequence thereof being in turn that the differential pressure limiter will close. Pressure build-up is decelerated. This phenomenon occurs in particular when the brake fluid is cold and has a high viscosity, at which time a slow pressure fluid speed will suffice to generate the critical pressure difference across the inlet valve.